Process of producing isoprene.



UNITED STATES PATENT OFFICE.

GEORG MERLING AND HUGO KGHLER, OF ELBERFELD, GERMANY, ASSIGNORS T FAR- BENFABRIKEN VORM. FRIEDR. BAYER/81;- CO., OF ELBERFELD, GERMANY, A COR- PORATION or GERMANY.

' PROCESS OF PRODUCING- ISOPRENE.

No Drawing.

' To all whom it may concern:

Be it known that we, Gnone MERLING and HUGO KoHLER, doctors of philosophy, chemists, citizens of the German Empire, residing atElberfeld, Germany, have invented new and useful Improvements in Processes of Producing Isoprene, ofwhich the following is a specification.

' We have found that isoprene may be obtained from alpha-beta-dimethylallyldime- Specification of Letters Patent.

thylamin by converting the latter (obtainable from alpha-beta-dimethyl-trimethylenedimethylammonium hydroxid) into completely alkylated alpha-beta-dimethylallyltrimethyl ammonium base and decomposing this base into isoprene, trimethylaminand water.

. The following formulae illustrate the process which probably takes place:

on, on,

CH; CH CH A]pha-beta-dimethylallyldimethylamin.

um base.-By treatment with the theoretical amount of freshly prepared silver oxid, alpha betadimethyltrimethylene dimethylammonium iodid (melting point 191 C.)

in aqueous solution is quicklyconverted into the corresponding ammonium hydroxid and iodid of silver. The filtered solution is distilled which starts at once the decomposition of the ammonium hydroxid into water and alpha-beta-dimethylallyldimethylamin CH2==C CH-N The latter distils overlwith steam as an oil scarcely soluble in water. The distillate 40 is neutralized with hydrochloric acid or with tartaric acid and then concentrated. The base is liberated by caustic potash, dried over caustic potash and purified by distillation. In simpler andquicker manner the base can be obtained from the alpha-beta-. d-imethyl trimethylenedimethylammonium """iodid,*chlorid,.or bromid by heating Wi an excess of pulverized caustic potash in an oil Isoprenel bath with or without the addition of a small Patented Aug. 27, 1912. Application-filed November 21, 1911. Serial No. 661,534.

the v odor, which boils under atmospheric pressure at from .105-106 C. and decolorizes permanganate in dilute sulfuric acid solution. The base combines with methyl iodid under a strong evolution of heat to alphabeta dimethyl allyl-trimethylammonium iodid, which is easily soluble in cold and Warm alcohol and crystallizes therefrom in leaves from the melting point 138-l40 G. without decomposition.

' Second phase of reaction, decomposition into isoprene. Alpha beta-dimethyl-allyl: trimethylammonium iodid (melting point at from 138140. C.) isconverted into the ammonium hydroxid in the manner described above. This product is decomposed by distilling the aqueous solution, or the ammonium halogenid is directly heated with pulverized caustic potash, calcium oxid or barythydrate under suitable addition of a small quantity of -alcohol or water, whereby separated from trimethylamin by treating it with diluted sulfuric acid,1dried over calcium chlorid and purified by distillation 1 In testimony whereof we have herelinto 10 over metallic sodium. It boils at from M set-our hands in the presence of two sub- 1 to 35 C. I scribing Witnesses.

T li e i e s?cf p10 lucing isoprene hich GEORG MERLING' [L'S'] 5 l L w y I comprises completely alkylating alpha-beta- HUGO KOHLER dimethyla-llyl-dimethylamin, and decompos- Witnesses: ing the resulting quaternary ammonium HELEN NUFER,

compounds, substantially as described. 7 ALBERT NUFER. 

